This project is concerned with a study of the effects of glucocorticoids in two types of neoplastic cells cultured in vitro, namely, epithelioid substratum-adherent cells and suspension-grown cells of lymphoid origin. The epithelioid cells are being used to study the evidence for the involvement of mevalonate in the regulation of surface glycoproteins. As already shown, addition of glucocorticoids to the cells grown in media containing delipidized serum results in a stimulation of HMG-CoA reductase followed by an increase in cellular dolichols and mannolipids. This leads to an increased incorporation of carbohydrates into cellular proteins. In some cases the increased protein glycosylation induced by the addition of glucocorticoids may be blocked by compactin, a competitive inhibitor of HMG CoA reductase, and the block may be reversed by exogenous mevalonate. The future work will concentrate on the identification of the glycoproteins affected by dexamethasone, particularly those which play a role in cell adherence. The investigations of the lymphoid cell system are now concerned with the effects of dexamethasone on phospholipid methylation in relation to their growth rate and their possible relationship to lymphocytolytic effects of glucocorticoid steroids.